Carrier-wave telegraphy



Dec. 13, 1927. 1,652,549

P. l. WOLD CARRIER WAVE TELEGRAFHY Original Filed Sept. 30, 1919 2Sheets-Sheet l I //7ve/7/0r: Pe/er l Vo/d.

Dec. 13, 1927. 1,652,549

P. I. WOLD CARRIER WAVE TELEGRAPHY Original Filed $ept. so, 1919 2Sheets-Sheet 2 llllllllrllllv Pe/er VVo/G Af/ja Patented Dec. 13, 1927.

UNITED STATES 1,652,549 PATENT OFFICE.

PETER I. WOLD, 0F SCHENECTADY, NEW YORK, ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

OARRIER-WAVE TELEGBAPHY.

Application filed September 30, 1919, Serial No. 327,435; Renewed Kay14, 1927.

The present invention relates to distant control of apparatus by wavesof electrical energy for signaling or other purposes. A particularobject of the invention is to provide method and means whereby areceiving operator in a simplex or a multiplex wave transmission systemmay give an indication to a sending operator during the progress of thetransmission.

In an application of Burton W. Kendall, Serial No. 334,682, filedOctober 31, 1919, there is described a wave transmission system adaptedfor signaling, in which it is necessary for the receiving operator tokeep his F key closed in order to receive signals and to enable thesending operator to hear his own signals. With the receiving operatorskey open, as in breaking in, neither operators receiver responds tofurther actuation of the sending operators key, and the system so far asthe operators are concerned is therefore analogous to the Morse closedcircuit system. To the same extent the present invention may be said toresemble the open circuit Morse system in that the receiving operatormay break in on his sending operator by depressing his key and holdingit closed, the key when not sending being open at its front contact.

A better understanding of the invention may be had from the followingdetailed description of an embodiment of the invention, taken inconnection with the drawing, of which Fig. 1 is a schematic circuitdiagram of a system according to the invention, and

2 and 3 show modifications of the system of Fig. 1.

Referring first to Fig. 1, stations S and S are adapted for independenttwo-way communication over the line 1 with stations S and Srespectively. Other similar stations may be associated with the line 1and may be adapted for selective intercommunication. Stations S and Sare not shown in detail in the drawing since they are similar to S and Swhich are shown and are below described in detail.

Line 1 is provided with nets 2 and 3 for balancing for all thetransmitted frequencies, and with line coils 4 and 5 for coupling thesending and receiving sets in balanced relation to one another. Fortransmission to the line 1, stations S and S feed into the branch 6which contains coils 7 inductively related to the line coils 4, and forreceiving from the line 1, stations S and S are associated with thebranch 8 which is bridged across the line. Stations S and S have similarbranch circuits 9 and 10 respectively.

Stations S and S have generators 11 and 12 respectively which producewaves of the same or different frequencies, preferably of slightlydiiferent frequencies to permit of easier selections betweentransmissions in the opposite directions.

By actuating key 13 at station S for transmitting signals, the generator11 is connected for different intervals to the circuit 14, which may betuned, if desired, to the generator frequency. Circuit 14 is coupled tocircuit 15 also tuned to the frequency of generator 11.. The wave trainsthus sent out from the generator 11 are impressfd through the coils 7and 4 upon the Because of the conjugate arrangement of the net and coils4 and 7, the wave from generator 11 does not pass into circuit 8, butafter traversing the line it passes into branch 10 across which are thetuned branches 16, 17 etc. Branch 16 is tuned to the frequency of thewave from generator 11, and this wave is therefore selectivelytransmitted to the tuned circuit 18, which is coupled to the branch 16as shown and is also tuned to be selective to the wave from generator11. Circuit 18 is connected through the normally closed back contact ofdouble-point key 19 to the input terminals of the amplifier A from whichthe wave passes in amplified form to the detector D By the well-knownaction of the detector each wave train received over the line isconverted into a more or less continuous current in the output of thedetector and is thus rendered capable of actuating relay 20. Relay 26therefore responds to the actuation of the distant sending key 13 andmay, by a local circuit as indicated, control any desired type ofreceiver, such as the usual sounder.

To transmit from station S to S key 19 is actuated and at its frontcontact closes the circuit of generator 12 and causes the transmissionof a wave from source 12 through circuits 21 and 22, preferably tuned,through branch 9 and to the line 1. At station S this wave is selectedby the tuned branch 23, and the key 13 being in its normal or upposition, the wave is impressed through the resonant circuit 24 upon theamplifying and detecting circuit comprising A and D by which the wave 15enabled to actuate relay 25 in the manner indicated in connection withdetector 1),.

In addition to each transmitters control of the distant receiver,provision is made whereby the sending operator hears in his own receiverthe signals which he is transmitting. For this purpose in the system ofFig. 1, coil 26 is included in the circuit 1 1 so that when the key 18is depressed energy is fed from generator 11 through coil 26 and throughcoil 27 coupled thereto and ineluded in the input circuit of detector Dso that relay 25 is actuated by this energy. This method of producingside tone in the 'local receiver is especially adapted for use withstaggered carrier frequency, in which case the circuits 23 and 24 areselective of a frequency or of frequencies different from that ofgenerator 11. The wave from generator 11 is made to affect relay 25,however, by being impressed upon the input circuit of the detector Dover a path which does not include the selective circuits 23 and 24-. Ina similar manner, when the key 19 at station S is depressed the distantrelay 25 will be actuated and, by virtue of the coupling 27, the localrelay 20 will also be actuated.

If during the transmission from station S to S for instance, theoperator at S wishes to break in on the sending operator, the key 19 isdepressed and is held down, where-- upon a continuous wave fromgenerator 12 is thrown on the line. When the key 13 is on its backcontact, i. e., between signals, the circuit 24. is connected to theinput terminals of amplifier A The wave incoming from generator 12 is,therefore, impressed on amplifier A and the sending operator hears inhis local receiver reverse signals as well as the signals transmitted byhim. With proper adjustment of the contacts of key 13 and the receivingcircuit, the relay 25 could be made to keep the receiver continuouslyin. the marking condition, whether that be the open or closed condition,by the alternate application of energy from generators 11 and 12, andthe sending operator would cease to hear his si nals entirely.

The presence of side tone by virtue of the coupling 26, 27 or similarmeans, it should be noted, is not necessary to the provision forbreaking in. If there is no side tone, the sending operator does nothear his own signals. If the receiving operator depresses his key,however, the sending operator hears signals the reverse of those beingsent by him in his local receiver, due to the closure between signalelements of his key 13 at its back contact. In either case he isnotified of the fact that the receiving operator has his key 19depressed. The sending operator therefore stops sending and releases hiskey 13 which is held in its up or normal position, thus placing hisreceiver circuit under control of the distant operators key so thatsignals may be received from the distant station S In similar manner,stations 5, and S and other intercommunicating stations if provided maybe arranged for similar cooperation with each other over the line 1, itbeing understood that the generators for transmitting and the receivingcircuits in stations S and S and other stations employ frequenciesdifferent from those used by stations S and S and each other. In otherrespects the stations may be alike.

' In Fig. 2, a different manner of producing side tone in the localreceiver is shown. No special circuit is used for transferring en ergyfrom generator 11 to the receiving circuit, but the line 1 and net 2 areadjusted for a slight unbalance so that when energy from generator 11 isimpressed on the line through coils 7 and 4 a portion of its passes intobranch 8, since, on account of the unbalanced condition, circuit 8 is nolonger bridged across points of equal potentials with respect to thewave from generator 11.

In case the same frequency is used for transmission in both directionsover the same channel of line 1, a simple tuned circuit, such as 23 inFig. 1, would serve to select the wave from generator 11 as well as thatfrom generator 12. However, if a different frequency is used fortransmission to station S from that generated by generator 11, it isnecessary to use a selecting circuit in branch 8, which will pass boththe transmitting and receiving frequencies. The hand filter 28 is shownfor that purpose, and it is so proportioned as to pass waves that areimpressed on branch 8 either from the local generator 11 or from adistant station S so that relay 25 is actuated by either wave. Thisfilter comprises tunin'g elements, such as inductance or capacity orboth, in series with the branch circuit and in shunt of the branch. Fordetails as to the design and construction of such a filter the UnitedStates patent to G. A. Gampbell, No. 1,227,113, granted May 22, 1917,may be consulted.

By depressing key 13, which in this instance may be a single-point key,current from generator 11 is thrown onto line 1. At the distant stationS the incoming current will be transmitted" through a band filter whichmay be entirely similar to 28. After being amplified, the receivedcurrent is detected, as described in the case of Fig. 1, to causeactuation of the receiver similar to relay 20 of Fig. 1. At the sametime, as above explained, some ofthe energy being transmitted fromgenerator 11, by virtue of the unbalance of the conjugatelyassociatedcoils 4: and 7, will pass into branch 8, will be selectivelytransmittedby filter 28, and will actuate relay 25. In order to simplify thedrawing the necessary amplifying and detecting devices are not shown inFig. 2. The

'wave of different frequency from the transmitter of station S is alsoselectively transmitted by} the filter 28 and hence, as in the case ofFig. 1, both the local and the distant receivers are controlled bysignal trains supplied to the line at either station. The mutilation ofthe signals in the local receiver during transmission, or the continuedenergization of the receiving relay, or the silencing of the receiver asheretofore indicated will be a notification to the sendmg operator of abreak signal from the distant station. At station S a band filter 29 isindicated which may be adapted to pass both the transmitted and receivedwaves for station S In both of the arrangements thus far shown a singlenet 2 has been used to balance the line 1 for all the transmittedfrequencies. In Fig. 3 a net 30 and a branch 31 are provided for eachtwo-way channel. The band filter 32, which may be siimlar to the filter28 above described, selectively passes between the line 1 and station Sall'the frequencies transmitted from and to that station.

By depressing key 13 the wave from generator 11 is impressed on the line1 through branch 31 and filter 32, and a portion of the energy istransmitted through coil 33 and coupling 27' to the detector D so thatrelay 25 is actuated in accordance with the outgoing signals. Incomingwaves from the distant station S pass through coupling 34. to theamplifying and detecting circuit and actuate relay 25 as before. Insteadof using the coil 33 and coupling 27, these elements might be omittedand the net 30 adjusted for a slight unbalance so that some of theoutput energy from generator 11 would be fed through coupling as to thelocal detectingcircuit.

The invention has been disclosed with par ticular reference tosignaling, but it is equally adapted for distant control of apparatus ofany desired nature. Also the waves employed may be radiated waves,instead of waves conducted over a line.

The invention is not to be limited either by the particular circuitarrangements as a whole as they have been illustrated and described orby the specific details, but only by the scope of the appended claims.

What is claimed is:

1. A signaling system comprising two stations connected by atransmission medium, a transmitter and a detector at each of saidstations, the transmitters at different stations being arranged totransmit difl'erent frequencies, and means controlled by each of saidtransmitters for rendering said detectors selectively responsive to eachof said transmitters actin alone.

2. A s1gn ing system having stations, 8. transmission medium for thetransmission of waves between said stations, a transmitter at onestation for transmitting a wave of given frequency, a receiver at saidstation, a transm1tter. at another station for trans mitting a wave of asubstantially difi'erent frequency, a selective circuit between saidreceiver and said medium for selectively transmitting the wave ofdifferent frequency to cause the actuation of said receiverindependently of the wave produced at the local transmitter, and meansto cause the actuation of the receiver by waves from the localtransmitter independently of said selective circuit.

3. A line having a high frequency channel for two-way transmission ofsignals between stations, a transmitter and a receiver for said channelat each station, means for balancing said line for the transmitted andreceived high frequencies, and means whereby the receiver at eachstation is responsive to the transmitter at that station acting alone,and selectively responsive to said transmitter at another station actingalone.

4:. A signaling system comprising two stations connected by atransmission medium, a transmitter and a detector at each of saidstations, the transmitters at different stations being arranged totransmit different frequencies, and means controlled by the transmitterat each of said stations for rendering the detector thereat alternatelyresponsive 'to the local and distant transmitters acting alone.

5. In a two-way wave transmission system, a line for conveying aplurality of waves of different frequencies, transmitters and receiversfor said line, selective receiving circuits associated with each of saidreceivers, means inluding balancing nets for said line for associatingsaid transmitters and receivers with said line, each transmittercomprising means for impressing wave trains upon said line and upon alocal one of said receivers, and means operative between thetransmission of said wave trains for rendering said receiver responsiveto a wave received over said line.

6. Asignaling system comprising a plurality of stations connected by atransmission medium, a transmitter and a receiver at each of saidstations, a selective receiving circuit at each of said stationsnormally associated with the receiver thereat, and means controlled byeach of said transmitters for disassociating the respective receiversfrom their receiving circuits and for simultaneousl rendering saidreceivers responsive to tile local transmitter independently of thelocal selective receiving circuit.

7. A two-way wave transmission system comprising a plurality ofstations, a source of waves, a selective circuit and a receiver at eachstation, connections for impressing a received-wave from another stationupon the selective circuit at one station to actuate selectively saidreceiver, andiconnections for actuating the receiver at the same stationby impressing the wave from said source thereupon independently of saidselective circuit.

8. In a two-way wave transmission system, the method which comprisescontrolling a receiver by either the local or a distant transmitteracting independently and shifting the said control from one to. theother of said transmitters between each two signal elements in order topermit the receiving operator to break in on the transmitting operator.

9. In a two-way Wave transmission system, the method which comprisestransmitting currents of frequencies individual to each transmitter,controlling a-receiver by either the local or a distant transmitteracting independently and shifting the said control from one to the otherof said transmitters between each two signal elements.

10. In a two-way wave transmission system having stations, atransmitter'at each station for transmitting currents of frequenciesindividual thereto, a receiver at each station controlled both by thelocal and a distant transmitter, said local and distant transmitterseach exerting its control by supplying currents of substantiallydifferent frequencies and means for actuating the receiver at eachstation by each signal element transmitted by the local transmitterindepend-' ently of said distant transmitter and for placing saidreceiver under control of said distant transmitter between each two ofsaid signal elements.

11. A signaling system comprising a plurality of stations connected by atransmission medium, means at each station for transmitting a wave of adistinctive frequency, a receiver at each of said stations, means tocause the selective actuation of said receivers by the wave transmittedfrom only one of the other stations, and means controlled by thetransmitting -means at each of said stations for rendering the receiverthereat unresponsive to incoming Waves and for rendering said receiverresponsive to waves from the local transmitter.

12. A signaling system comprising two stations connected by atransmission medium, a normally open circuit including a source ofcurrent at each of said stations, a selective receivin circuit and areceiver at each of said stations, a coupling between said normally opencircuit and said receiver, and a key at each of said stations adapted inone position to connect the receiver with the selective receivingcircuit thereat, and in another position to close the normally opencircuit to supply current to said transmission medium and to saidreceiver.

13. A two-way wave transmission system comprising a plurality ofstations, a source of waves, a selective circuit and a receiver at eachstation, a key adapted in one position to associate said receiver withsaid selective circuit whereby to impress received waves from anotherstation upon said receiver, and means adapted in another position ofsaid key to connect said receiver in circuit with the local source ofwaves independently of said selective circuit.

14. A two-way wave transmission system comprising a plurality ofstations connected by a transmission medium, a source of waves ofdistinctive frequency at each station, a selective receiving circuit anda receiver at eaclLof said stations, said receiving circuits being tunedto the frequency of the waves transmitted from only one of the otherstations, a key at each of said stations adapted in one position toassociate the receiver with the selective circuit thereat whereby toimpress received waves of predetermined frequency upon said receiver,and means adapted in another position of said key to connect the localsource of waves in circuit with the receiver independently of theselective receiving circuit thereat.

15. A signaling system comprising a line,

a plurality of stations associated therewith,

PETER I. WOLD.

